C / C++ / MFC

Re: Please please help with this simple Q from a C++ newbie

19-Feb-09 10:11

Please please help with this simple Q from a C++ newbie....I spent hours trying to find the answer online...

I want to run this on a linux box. Open a file containing a list of file names and then run a linux commands on each of the list for example:
The file contains a list of files names eg:

test
test1
test2
test3

How do I code in C so that it opens the file and then foreach of the elements do a system command eg: ls

in perl it would be something like:

#!/usr/local/bin/perl

while(<>){
chomp;

$cmd="ls $_";
system($cmd);
print "$cmd\n";
}

Thanks in advance!

Stuart Dootson19-Feb-09 10:35

Re: Please please help with this simple Q from a C++ newbie

19-Feb-09 10:35

Use fgets to read individual lines from a file.

Use strcat to append the file name to the command (just make sure the command is in a long enough string to start with).

C has a system function just like Perl as well.

It's easier in C++, using std::getline to read lines from a file and the std::string class to build the command:

#include <stdlib.h>
#include <iostream>
#include <fstream>
#include <string>

int main(int argc, char** argv)
{
  std::ifstream f(argv[1]);
  
  std::string s;
  while (std::getline(f, s))
  {
    system((std::string("ls -l ") + s).c_str());
  }
}

Easy enough (and works on OS X, which is close enough to Linux)

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

meixiang619-Feb-09 10:53

Re: Please please help with this simple Q from a C++ newbie

19-Feb-09 10:53

Thanks very much Stuart!

Any chance of typing the entire code in C as well?

thanks a lot again!

Stuart Dootson19-Feb-09 11:42

Re: Please please help with this simple Q from a C++ newbie

19-Feb-09 11:42

meixiang6 wrote:
Any chance of typing the entire code in C as well?

I'll leave that as an exercise for the reader...you remember I said it was easier in C++ Smile | :)

It's not too much different - fgets is roughly equivalent to getline. Rather than adding string objects together, you use strcpy to copy the command into a character buffer, then strcat to add the line you've read from the file to the end of the buffer. Then you pass the buffer to the system command.

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

meixiang619-Feb-09 12:00

Re: Please please help with this simple Q from a C++ newbie

19-Feb-09 12:00

thanks Stuart for the information, I am a very new newbie and have no idea how that looks like in C, any chance of someone writing that in C ?

apologizes for the inconvenience

Stuart Dootson19-Feb-09 12:17

Re: Please please help with this simple Q from a C++ newbie [modified]

19-Feb-09 12:17

You'll gain a lot more learning how to do it yourself.

This page[^] has code that reads a file line by line (search for 'fgets').

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

meixiang619-Feb-09 14:39

Re: Please please help with this simple Q from a C++ newbie

19-Feb-09 14:39

Thanks Stuart, I got it working with this, not sure if the code is right thou but it works...

#include <stdio.h>
#include <string.h>

int main()
{
FILE *f;
char string[1000];
char str[1000];
f = fopen("file.txt", "r");
if(!f) {
printf("Couldn't open file.txtn");
return 1;
}
while(fgets(str, 1000, f)) {
/* printf("%s", str); */
strcpy (string, "ls -la ");
strcat (string, str);
system (string);

}
fclose(f);
return 0;
}

<div class="ForumMod">modified on Thursday, February 19, 2009 8:56 PM</div>

David Crow19-Feb-09 17:08

David Crow

19-Feb-09 17:08

meixiang6 wrote:
char string[1000];

I know this is being nit-picky, but you might want to make this 7 bytes larger than str. If str contains 999 bytes, copying that plus "ls -la " is going to overflow string.

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Re: Please please help with this simple Q from a C++ newbie

Stuart Dootson19-Feb-09 21:43

19-Feb-09 21:43

Aside from what David said, that code's fine Smile | :)

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

urgent : I need help

D_Isaac19-Feb-09 9:38

D_Isaac

19-Feb-09 9:38

am a newbie to win32 console programming and i was given
to
Create the editor of resources files of application, which allows to form the following facility

-the icon
- the menu
- the text
- the dialogue windows

i was able to write a code to for the text but i cant for the icon , i really dont have idea.

Please help so we could share ideas together thanks

CPallini19-Feb-09 11:01

19-Feb-09 11:01

As newbie, they could give you as well the task to discover the origin of the Universe, I suppose.
My solidarity. Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

Luc Pattyn19-Feb-09 11:41

19-Feb-09 11:41

CPallini wrote:
discover the origin of the Universe

No problem, it is where it always has been: at (0, 0, 0, 0).
You may add more dimensions if you are so inclined.

Smile | :)

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- before you ask a question here, search CodeProject, then Google
- the quality and detail of your question reflects on the effectiveness of the help you are likely to get
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led mike19-Feb-09 11:44

led mike

19-Feb-09 11:44

Luc Pattyn wrote:
it is where it always has been: at (0, 0, 0, 0).

What is that RGBA values?

Luc Pattyn19-Feb-09 11:54

19-Feb-09 11:54

It holds true for both xyzt and ARGB (those were the really dark ages).

Smile | :)

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led mike19-Feb-09 11:56

led mike

19-Feb-09 11:56

Luc Pattyn wrote:
those were the really dark ages

Now you're getting the hang of it! That's as bad as anything I could come up with. Big Grin | :-D

Luc Pattyn19-Feb-09 12:01

19-Feb-09 12:01

So it's good I reckon Cool | :cool:

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CPallini19-Feb-09 12:22

19-Feb-09 12:22

Welcome in the THHB [^]
(unfortunately, at the moment, I'm not able to add a welcome message in my blog).
Big Grin | :-D

led mike20-Feb-09 5:28

led mike

20-Feb-09 5:28

To be honest, I didn't think I understood the meaning of the list since I wasn't already on it. Laugh | :laugh:

Rick York19-Feb-09 12:55

Rick York

19-Feb-09 12:55

With an alpha value of 0 I think that would have been the really transparent ages.

Cool | :cool:

Luc Pattyn19-Feb-09 13:19

19-Feb-09 13:19

Yep, however without any light the difference is futile.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

CPallini19-Feb-09 21:51

19-Feb-09 21:51

That's never true, there are the (A)RGB space vacuum fluctuations... Roll eyes | :rolleyes:

CPallini19-Feb-09 12:11

19-Feb-09 12:11